Cosmetic Dermatology - part 2 pot

Unexpectedly, there was a near doubling of mortality, from 20 to 38%, in both studies. 1.11 A Brief Guide to Anti-Aging Supplements and Growth-Hormone-Releasing Nutrients for the Skin Updated recommendations, developed in a col- laboration between the United States and Can- ada, incorporate three types of values: the estimated average requirement (EAR), the recommended dietary allowance (RDA), and the tol- erable upper intake level (UL). Collectively, these values are referred to as dietary reference intakes (DRIs). EAR is the intake value that is estimated to meet the requirements of a defined indicator of adequacy in 50% of the population (note that this means that the needs of 50% of the population are not being met). RDA is the dietary intake level that is sufficient to meet the nutrient requirements of nearly all individuals in the group. UL is not intended to be a recommended level of intake but represents the highest level of intake that is unlikely to have any adverse health effects in most individuals. It is important to note that the UL is not meant to apply to individuals receiving supplements under medical supervision and should not be used to limit doses investigated in clinical trials [42]. DRIs for antioxidant nutrients were developed by considering the roles of antioxidant nutrients in decreasing the risk of diseases, including chronic diseases and other conditions, and by interpreting the current data on intakes in the United States and Canada. 1.12 Oral Antioxidant Nutrients In light of new research on the importance of these vitamins to overall health, the Institute of Medicine (IOM) in Washington, D.C., recently released new dietary guidelines for intake of the antioxidant nutrients vitamin C, vitamin E, carotenoids, and selenium. In addition, a variety of other nutrients are believed to be involved in antioxidant processes.According to the IOM, a dietary antioxidant is defined as “a substance in foods that significantly decreases the adverse effects of reactive species, such as reactive oxygen and nitrogen species, on the normal phys- iological function in humans” [43]. 1.12.1 Vitamin C Vitamin C is the predominant plasma antioxidant. This water-soluble vitamin scavenges plasma free radicals and prevents their entry into low-density lipoprotein (LDL) particles [44]. Vitamin C regenerates active vitamin E and increases cholesterol excretion and im- proves endothelium-dependent vasodilation and reduces monocyte adhesion. Supplementa- tion with vitamin C (1,000 mg) and vitamin E (800 IU) before the ingestion of a high-fat meal has been found to reverse endothelial dysfunc- tion and vasoconstriction following the meal. On the skin, the function of vitamin C is the production of collagen, which forms the basis for connective tissue in bones, teeth, and cartil- age. It also plays an important role in wound healing, immunity,and the nervous system,and acts as a water-soluble antioxidant. Because vitamin C is water soluble, its antioxidant functions take place in aqueous body compart- ments. It also helps protect low-density lipoprotein cholesterol (LDL-C) against free radical damage. As an antioxidant, it helps protect against cancer [43], CVD [45, 46], and certain effects of aging [47]. Severe deficiency of vitamin C leads to scurvy, which includes symptoms of bleeding gums, joint pain, easy bruising, dry skin, fluid retention, and depression. Marginal deficien- cies may play a role in the development of cancer [48, 49], CVD [50], hypertension [51], decreased immunity, diabetes [52], and cataracts [53]. The RDA for vitamin C is 75 mg/day for women and 90 mg/day for men. Smokers require an additional 35 mg/day due to increased oxidative stress and other metabolic differenc- es. The UL for vitamin C is 2,000 mg/day [43]. It remains possible that higher vitamin C intake may be beneficial in the treatment or prevention of certain diseases, particularly cancer and respiratory disorders. Rafaela M. Quiroga 10 1 1.12.1.1 Food Sources Important sources of vitamin C include citrus fruits, strawberries, kiwifruit, papaya, and vegetables such as red peppers, broccoli, and brus- sels sprouts. Vitamin C can easily be destroyed during cooking and storage; therefore, food handling and preparation can have a signifi- cant effect on vitamin C content. 1.12.1.2 Risks with High Doses Vitamin C is relatively safe at high doses, but intake of doses higher than 2 g/day may result in diarrhea, nausea, stomach cramping, excess urination, and skin rashes [54]. More recently, 4 g/day has been said to be well-tolerated and safe, except in some patients with renal dys- function [55]. In rare cases, daily 2-g doses have been associated with kidney stones [56]. Intake of greater than 1 g/day increases oxalate excretion without clinical consequence in normal healthy individuals but could lead to adverse consequences in those with underlying renal disease. Dietary needs of vitamin C are increased by smoking, pollutants, aspirin, alcohol, estrogen, antibiotics, and corticosteroids. It may also interact with various laboratory tests, causing false readings [7]. 1.12.2 Vitamin E Vitamin E is the name given to a group of eight fat-soluble compounds. The most abundant form of vitamin E is α-tocopherol, and this is the only form that is active in humans [43]. However, research suggests that the mixed forms found in food may be more beneficial than the isolated α-tocopherol form that is used in some supplements [7]. Vitamin E supplements are available in natural forms from soybean or wheat germ oil, indicated by a “d”prefix (also referred to as the ster- eoisomer RRR-a tocopherol), and synthetic forms manufactured from purified petroleum oil, indicated by a “dl” prefix (which includes eight stereoisomers of α-tocopherol, four 2R- stereoisomers, and four 2S-stereoisomers). The most active and available form of vitamin E is α-tocopherol. Vitamin E is the predominant antioxidant in LDL. This vitamin also inhibits platelet activation and monocyte adhesion. 1.12.2.1 Role in the Body and Consequences of Deficiency The primary role of vitamin E is to act as an antioxidant. Vitamin E is incorporated into the lipid portion of cell membranes and other molecules, protecting these structures from oxidative damage and preventing the propagation of lipid peroxidation [11]. Vitamin E appears to have protective effects against cancer [35], heart disease [4], and complications of diabetes [4]. It is necessary for maintaining a healthy immune system [57], and it protects the thymus and circulating white blood cells from oxidative damage. Also, it may work synergistically with vitamin C in enhancing immune function [5]. In the eyes, vitamin E is needed for the development of the retina and protects against cataracts and macular degeneration [58]. Vitamin E deficiency is rare and occurs mostly in people with chronic liver disease and fat malabsorption syndromes such as celiac disease and cystic fibrosis. It can lead to nerve damage, lethargy, apathy, inability to concen- trate, staggering gait, low thyroid hormone levels, decreased immune response, and anemia. Marginal vitamin E deficiency may be much more common and has been linked to an increased risk of CVD and cancer [42]. 1.12.2.2 Recommended Daily Allowance Of the fatty acids, polyunsaturated fatty acids are most likely to undergo oxidation in the presence of oxygen or oxygen-derived radicals. The necessary amount of vitamin E depends on the amount of polyunsaturated fatty acids in the diet. The greater the amount of these fats in Chapter 1 Anti-A ging Me dicine As It R elat es to De rmat ology 11 the diet, the greater the risk they will be dam- aged by free radicals and exert harmful effects. Because it is impossible to obtain a high intake of vitamin E without consuming a high-fat diet, use of vitamin E supplements is often recommended [4]. 1.12.2.3 Food Sources The best sources of vitamin E are certain vege- table oils (including wheat germ oil, hazelnut oil, sunflower oil, and almond oil), wheat germ, whole grain cereals, and eggs. 1.12.2.4 Risks with High Doses According to the IOM, vitamin E is relatively safe at doses as high as 1,000 mg/day [11], Short-term administration of doses as high as 3,200 mg/day has not been found to be toxic, but adverse effects have been reported with ex- tended intake of 1,100–2,100 mg/day of α-tocopherol [11, 43]. Reported adverse effects include increased risk of bleeding, diarrhea, ab- dominal pain, fatigue, reduced immunity, and transiently raised blood pressure. Some research suggests that very high doses may be pro-oxidant (i.e., acting as free radicals), espe- cially in smokers [45, 46]. 1.12.2.5 Interactions with Other Nutrients and Drugs Vitamin E exerts antioxidant effects in combination with other antioxidants, including β- carotene, vitamin C, and selenium. Vitamin C can restore vitamin E to its natural reduced form. Vitamin E is necessary for the action of vitamin A and may protect against some of the adverse effects of excessive vitamin A. Because inorganic iron destroys vitamin E, the two should not be taken simultaneously. Cholesty- ramine, mineral oil, and alcohol may reduce the absorption of vitamin E [44]. Based on the results of a single case report, there has been concern that coadministration of vitamin E with anticoagulants (e.g., warfarin) may enhance their effects [44, 47]. However, a randomized clinical trial that investigated the effects of vitamin E administration in patients on long-term warfarin therapy found no signif- icant change, and the researchers concluded that vitamin E may safely be given to patients receiving warfarin [48, 49]. 1.12.3 Carotenoids Carotenoids (also referred to as carotenes) are a group of more than 600 highly colored plant compounds; however, only 14 have been identi- fied in human blood and tissue [50]. The most prevalent carotenoids in North American diets include α-carotene, β-carotene, lycopene, lutein, zeaxanthin, and β-cryptoxanthin. Only three (α-carotene, β-carotene, and β-cryptoxanthin) are converted to vitamin A and are con- sidered pro-vitamin A carotenoids [11]. 1.12.3.1 Role in the Body and Consequences of Deficiency The only specific effect of carotenoids in humans is to act as a source of vitamin A in the diet, but they also have important antioxidant actions. The latter are based on the carotenoids’ ability to quench singlet oxygen and trap per- oxyl radicals, thereby preventing lipid peroxidation [50]. As a result, carotenoids protect against the development of cancer, CVD, and ocular disorders. Carotenoids also affect cell growth regulation and gene expression. Diets low in carotenoids may lead to increased risk of cancer and heart disease. Lycopene is the most potent antioxidant for quenching single oxygen and scavenging free radicals [51]. Isotretinoin currently is approved for the treatment of nodulocystic acne, and there have been reported benefits in using 10–20 mg three times a week for 2 months for the treatment of cutaneous aging [59]. Rafaela M. Quiroga 12 1 1.12.3.2 Recommended Daily Allowance Currently, there are no DRIs for carotene intake, as it is believed that the current state of research on these nutrients is not strong and con- sistent enough to support any recommendations. An intake of -carotene 6 mg is needed to meet the vitamin A RDA of 1,000 mcg retinol equivalents (RE) [44]; RE is a measurement of vitamin A intake that allows for comparison of different forms of the vitamin. One IU of vitamin A is equivalent to -carotene 0.6 mcg [60]. Due to insufficient data demonstrating a threshold above which adverse events will oc- cur, no UL has been set for any carotenoid [6]. 1.12.3.3 Food Sources Primary sources of -carotene include carrots, sweet potatoes, pumpkin, cantaloupe, pink grapefruit, spinach, apricots,broccoli,and most dark green leafy vegetables; -carotene is not destroyed by cooking. Lycopene is abundant in tomatoes, carrots, green peppers, and apricots. Lycopene is concentrated by food processing and therefore may be found in high concentrations in foods such as processed tomato products (e.g., spaghetti sauce and tomato paste). Lutein is found in green plants, corn, potatoes, spinach, carrots, and tomatoes, and zeaxanthin is found in spinach, paprika, corn, and fruits. 1.12.3.4 Risks with High Doses Carotenoids are believed to be safe at fairly high doses. Some areas of skin may become orange or yellow in color (carotenodermia) if high doses of -carotene (30 mg/day or greater) are taken for long periods but will return to normal when intake is reduced [6]. This effect can be used therapeutically in clinical practice to treat patients with erythropoietic photopor- phyria (a photosensitivity disorder). Such patients have been treated with doses of approxi- mately 180 mg/day without reports of toxic effects [6]. Carotenes have enhanced bioavailabil- ity and have been associated with an increased risk of lung cancer in smokers. Interactions with other nutrients: Caroten- oids require bile acids in order to be absorbed. Conversion of carotenoids to vitamin A re- quires protein, thyroid hormone, zinc, and vitamin C. 1.12.4 Selenium 1.12.4.1 Role in the Body and Consequences of Deficiency The most important antioxidant mineral is selenium.Selenium is essential for the function of the antioxidant enzyme glutathione peroxi- dase, and it is also important for healthy immune and cardiovascular systems. Selenium’s anti-inflammatory properties have been demonstrated by its ability to inhibit skin-damaging, UV-induced inflammatory cytokines [61]. Results from a Nutritional Prevention of Can- cer trial conducted among individuals at high risk of nonmelanoma skin cancer demonstrated that selenium supplementation is ineffective at preventing skin cancer and basal cell carcinoma and that it probably increases the risk of squamous cell carcinoma and total nonmelanoma skin cancer. 1.12.4.2 Recommended Daily Allowance The RDA of selenium for men and women is 55 mcg/day, and the UL is 400 mcg/day. 1.12.4.3 Food Sources Dietary intakes depend on the content of the soil where plants are grown or where animals are raised. Good sources of selenium include organ meats and seafood. Because plants do not require selenium, concentrations of this antioxidant in plants vary greatly, and food tables that list average selenium content are unreliable for Chapter 1 Anti-A ging Me dicine As It R elat es to De rmat ology 13 plant foods. In the United States and Canada, the food distribution system ensures that re- gions with low selenium concentrations in the soil do not have low selenium dietary intakes [6]. 1.12.4.4 Risks with High Doses The UL for selenium is 400 mcg/day; toxicity is noted at mean doses greater than 800 mcg/day, with a 95% confidence limit of 600 mcg/day [62]. Doses above this range result in early symptoms of selenosis, including fatigue, irrita- bility, and dry hair [6, 63, 64]. More advanced symptoms include dental caries, hair loss, loss of skin pigmentation, abnormal nails, vomit- ing, nervous system problems, and bad breath [63]. 1.12.4.5 Interactions with Other Nutrients The combination of selenium and vitamin E seems to have synergistic effects for the treatment of heart disease, ischemia, and cancer.Vi- tamin C may also produce synergistic effects, but large doses of vitamin C may result in decreased absorption [65]. 1.13 Glycemic Index Overeating carbohydrate foods can prevent a higher percentage of fats from being used for energy and lead to a decrease in endurance and an increase in fat storage due to insulin. High insulin levels suppress two important hor- mones: glucagon and GH. The best solution to utilize more fats is to moderate the insulin response by limiting the intake of refined sugar and keeping all other carbohydrate intake to about 40% of the diet. The glycemic index (GI) is a measure of how much insulin increases after eating carbohydrates. High GI foods include sugar and sugar-containing foods, bagels, breads and potatoes, cereals, and other foods containing sugar maltose, as well as oatmeal, bran muffins, pasta, and bananas. Carbohy- drates with a lower GI index include pears, natural yogurt, lentils, grapefruit, peanuts, and fructose. 1.14 Final Remarks When approaching the patient with aging skin, the aim is not to make the skin simply appear smoother or less wrinkled but to make the en- tire body and mind appear or feel younger. References 1. Perez G, Tilly J (1997) Cumulus cells are required for the increased apoptotic potential in oocytes of aged mice. Hum Reprod 12 :2781–2783 2. Ashcroft G,Horan MA,Ferguson MW (1997) The effect of aging on wound healing: Immunolocaliza- tion of growth factors and their receptors in a mu- rine incisional model. J Anat 190 :351–365 3. Banks D, Fossel M (1997) Telomeres, cancer, and aging. 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Quiroga 16 1 Core Messages Chapter 2 Anti-Aging Skin Care Ingredient Technologies Jeannette Graf 2 2.1 Introduction The past decade has witnessed the progression of the field of cosmeceuticals moving toward one of cosmoleculars™. The impact of advanced technologies as well as pharmaceutical methods and drug delivery systems has resulted in the field of cosmetic dermatology. This chapter will attempt to give the practitioner a base of current knowledge in the field of cosmetic dermatology.The skin care consumer has been faced with a literal flood of products into the marketplace designed to address various cosmetic concerns. As research and development of new bioactive ingredients and knowledge of existing ingredients continue to grow, and new technologies reflect increased stability and delivery of these ingredients to the skin, this trend will only continue to grow. í The impact of bioactive skin care ingredient technology, pharmaceutical methods, and drug delivery systems have resulted in the development of cosmoleculars and the advancement of cosmeceuticals™ in anti-aging skin care ingredient technology. í Anti-aging skin care ingredients are assessed: antioxidants, hydroxy acids, beta glucans, minerals, peptides, and growth factors. í Topical antioxidants have both protective and rejuvenation benefits. Currently under research and development are spin traps (phenyl butyl nitrone). Contents 2.1 Introduction . . . . . . . . . . . . . . 17 2.2 Reassessing the Skin Care Regimen .18 2.3 Aging Skin . . . . . . . . . . . . . . . 18 2.4 Antioxidants . . . . . . . . . . . . . . 19 2.4.1 Spin Traps–Phenyl Butyl Nitrone . . . 19 2.4.2 Vitamin E . . . . . . . . . . . . . . . . 19 2.4.3 Vitamin C . . . . . . . . . . . . . . . . 20 2.4.4 Coenzyme Q10 . . . . . . . . . . . . . 21 2.4.5 Idebenone . . . . . . . . . . . . . . . . 21 2.4.6 Lipoic Acid . . . . . . . . . . . . . . . 21 2.4.7 Polyphenols . . . . . . . . . . . . . . . 21 2.4.8 Selenium . . . . . . . . . . . . . . . . . 22 2.4.9 Carotenoids . . . . . . . . . . . . . . . 22 2.5 Vitamin A–Retinoids . . . . . . . . . . 22 2.6 B Vitamins . . . . . . . . . . . . . . . 23 2.7 Alpha-Hydroxy Acids (AHAs) . . . . . 23 2.8 Polyhydroxy Acids (PHAs) . . . . . . . 24 2.9 Beta-Hydroxy Acids (BHAs) . . . . . . 24 2.10 Beta-Glucan . . . . . . . . . . . . . . . 24 2.11 Skin Respiratory Factors . . . . . . . . 24 2.12 Copper . . . . . . . . . . . . . . . . . . 25 2.13 Peptides . . . . . . . . . . . . . . . . . 25 2.14 Conclusion . . . . . . . . . . . . . . . 26 References . . . . . . . . . . . . . . . . 26 2.2 Reassessing the Skin Care Regimen The cosmetic and beauty industry is one of the world’s oldest professions, dating as far back as 1000 B.C. to the Picts, a tribe in Scotland. The use of ointments and oils was recorded on pa- pyrus by the Ancient Egyptians, and cold cream is said to have been invented by the ancient Greek physician Galen. The quest for beautiful skin will bring many patients seeking expert advice to the dermatologist’s office. The aim of this section is to try and simplify a topic that is constantly changing. Technologic advances of the past several decades have provided a great deal of information about skin structure and function as well as cellular and molecular mechanisms of aging. The skin’s appearance is dependent on many factors, including brightness and the way it re- flects light. Healthy looking skin and how it re- flects light is as important to younger-looking skin as is diminishing wrinkles. Lack of proper skin care can accelerate the aging process. It is therefore worthwhile to include a review of basic skin care, which comes down to cleansing and moisturizing. The stratum corneum (SC) is a highly specialized structure whose brick and mortar composition is made up of terminally differen- tiated corneocytes (brick) intertwined within a specialized lipid matrix (mortar), which forms the skin’s protective moisture barrier [1]. The SC is made up of dead corneocytes that are formed following apoptosis or planned death of migrating keratinocytes. The ability of the SC to retain moisture is through a variety of small- molecular-weight compounds collectively called the natural moisturizing factor (NMF) [2, 3]. The NMF functions as a humectant and consists of many compounds, including lactic acid, urea, and amino acids, which are break- down products of filaggrin and cis-urocanic acid whose role is not clear but is believed to have a free-radical-scavenging role [4, 5]. The highest levels of NMF are found in the lowest re- gions of the SC where the greatest amount of moisture is retained. The lipid matrix of the SC is made up of bipolar lipids in alternating hydrophilic and hydrophobic rows. The lipids consist of fatty acids, ceramides, and cholesterol, which form the SC mortar by surrounding the NMF thereby preventing moisture loss known as TEWL (transepidermal moisture loss.) Without this lipid bilayer, the hydrophilic NMF would evap- orate and the resultant TEWL would clinically result in dry and aged-looking skin. Cleansing is necessary in order to remove environmental dirt, microorganisms, makeup, and metabolic byproducts that can otherwise be damaging to the skin. Finding a cleanser ap- propriate for skin type that will not harm the moisture barrier while ensuring that a moistu- rizer is used to replenish and protect the moisture barrier is as important as any anti-aging ingredient. 2.3 Aging Skin How skin ages depends on a number of factors. The primary factor that determines the way a person ages is underlying genetics. Other internal influences include diet, lifestyle, drug, and alcohol history. Smoking, a cause of premature aging of the skin, has been directly linked with elevations in matrix metalloproteinase-1 (MMP-1), which is a zinc-dependent protease responsible for degradation of dermal collagen [6]. Environmental exposures,including weath- er changes and pollutants, have a direct impact on skin aging, with the most profound degrada- tive changes caused by chronic UV exposure with resultant photoaging. Chronically aged skin that loses the scaffold- ing of the dermal structural proteins elastin and collagen in addition to epidermal thinning appears loose and wrinkled. There is atrophy of adnexal structures with a decrease of oil-se- creting glands and the skin’s moisture retaining ability,resulting in dryness and scaling. Contin- ued loss of elasticity results in sagging, jowli- ness, and deep furrows. Photoaging compounds the structural changes by accelerating aging with even more pronounced wrinkling. There are more epidermal changes with pig- Jeannette Graf 18 2 mentary alterations of mottling and wrinkling than seen in chronologically aged skin alone. The question of how and why we age has been the subject of much thought and discus- sion.As we learn more about aging and cell-sig- naling pathways, the approach to aging evolves. If humans are built with internal repair mechanisms, why do we age with degenerative changes? Many scientists are now starting to view physical aging as a disease process. The cellular and molecular mechanisms involved in aging reveal an intricate series of signals, markers, and pathways, all of which are programmed to monitor and control the lifespan of a cell as it ages. By studying these molecular events and pathways, the field of anti-aging will be fur- thered by the use of cosmoleculars™. 2.4 Antioxidants The use of antioxidants in any anti-aging skin care regimen is essential in order to combat and prevent further damage. Vitamins have been used to combat free radical damage for many years. Unfortunately, they get used up rather quickly since it takes one vitamin to neutralize one free radical. Enzymes are more efficient free radical scavengers; however, they depend on the presence of a healthy cellular environ- ment and certain trace minerals to synthesize them. There is growing evidence of the synergy that exists in using combinations of antioxidants along with sunscreens. Some antioxidants have protective benefits while others work as protectants in addition to stimulating age-reversal changes. 2.4.1 Spin Traps–Phenyl Butyl Nitrone We are familiar with free radical damage that occurs with oxidative stress by sun, environmental pollutants,and cigarette smoking. How- ever, free radicals are formed as result of normal oxygen metabolism and therefore are a byproduct of normal physiologic function. Da- maging free radicals are created when an aberrant electron “spins” out of its orbit leaving a highly unstable molecule. The very newest antioxidants, which are known as “spin traps,” have the ability to catch or trap the aberrant electron as it starts to spin out of control and return it to its orbit before it can do any damage. Although the use of spin traps in dermatology is in its infancy, these compounds show a great deal of promise. Spin traps were originally used as a way to measure free radical activity both in vivo and in vitro through their ability to form stable com- plexes [7, 8]. Their uses in degenerative diseases associated with aging have been a subject of study due to their ability to trap and neutralize free radicals. The most well-known spin trap is phenyl butyl nitrone (PBN) [9]. Numerous studies by Dr. J. Carney and his associates have been performed that have demonstrated the anti-inflammatory, neuroprotective, age-re- versing effects of PBN. Interestingly, it is not so much their capacity to neutralize free radicals that is responsible for the protective behavior of spin traps but, rather, their ability to mod- ulate proinflammatory cytokines [10]. 2.4.2 Vitamin E Topically applied vitamin E plays an enormous role in protecting the skin from free radical damage. Vitamin E is the most abundant antioxidant found in skin, and it is produced in human sebaceous glands in its alpha- and gamma-tocopherol forms. These tocopherols are part of a natural protective mantle that has been described and is, in fact, the first line of protection against environmental stress. As the vitamin E levels of the skin diminish, the production of alpha- and gamma-tocopherols occurs in the sebaceous glands and is delivered to the skin’s surface via sebum [11]. Oxidative damage occurs when the rate of depletion of vitamin E exceeds the rate of production. The important role of sebaceous glands and sebum in the production and delivery of vitamin E to the skin may explain the often-made observation that oily skin tends to age more slowly than dri- er skin. Perhaps those with oily skin have a higher vitamin E level and therefore more natural protection than those with dry skin. Chapter 2 Anti-A ging Sk in Ca re Ingredient Te chnologies 19 [...]... al (20 01) Matrix metalloproteinase-1 and skin ageing in smokers Lancet 24 : 935–936 7 Floyd RA (20 00) Nitrone inhibition of age associated oxidative damage Ann NY Acad Sci 899 : 22 2 23 7 8 Floyd RA et al (20 02) Nitrones, their value as therapeutics and probes to understanding aging Mech Ageing Dev 123 (8) : 1 021 –1031 9 Carney and Floyd (1991) Protection against oxidative damage to CNS by alpha-phenyl-tert-butyl... (1999) Prevention of UVB-induced immunosuppression in mice by the green tea polyphenol (-) -epigallocatechin-3-gallate may be associated with alterations in IL-10 and IL- 12 production Carcinogenesis 20 : 21 17 21 24 34 Zhao JF et al (1999) Green tea protects against psoralen plus UVA-induced photochemical damage to skin J Invest Dermatol 113 : 1070–1075 35 Katiyar SK, Elmets CA (20 01) Green tea polyphenolic... Chapter 2 23 Takashima H et al (1971) Ascorbic acid esters and skin pigmentation Am Perfum Cosmet 86 : 29 –36 24 Pinnell SR (20 01) Topical l-ascorbic acid: Percutaneous absorption studies Dermatol Surg 27 : 137–1 42 25 Pinnell, Sheldon R (1988) New stabilized ascorbic acid solution–percutaneous absorption and effect on relative collagen synthesis Journal of Cutaneous Aging & Cosmetic Dermatology 1 (2) 26 Hoppe... Dermatol 29 : 43–51 30 Rijnkels JM et al (20 03) Photoprotection by antioxidants against UVB-radiation-induced damage in pig skin organ culture Radiat Res 159 (2) : 21 0 21 7 31 Beitner H (20 03) Randomized, placebo-controlled, double blind study on the clinical efficacy of a cream containing 5% alpha-lipoic acid related to photoageing of facial skin Br J Dermatol 149(4) : 841–849 32 Katiyar SK et al (20 00)... energizer Biofactors 9 : 37 27 DiNardo J et al (20 04) Antioxidants compared in a new protocol to measure protective capacity against oxidative stress part II, American Academy of Dermatology, Washington D.C 28 Moini H et al (20 02) Antioxidant and prooxidant activities of alpha-lipoic acid and dihydrolipoic acid Toxicol Appl Pharmacol 1 82( 1)84–90 29 Podda M (20 01) Activity of alpha-lipoic acid in the protection... photoprotectants Acta Derm Venereol 76 : 26 4 26 8 18 Chan AC (1993) Partners in defense, vitamin E and vitamin C Can J Physiol Pharmacol 71 : 725 –731 19 Phillips CL et al (19 92) Ascorbic acid and transforming growth factor-ß1 increase collagen biosynthesis via different mechanisms: coordinate regulation of pro-alpha 1(I) and pro-alpha 1(III) collagens Arch Biochem Biophys 29 5 : 397–403 20 Geesin JC et al (1988) Ascorbic... and type III procollagen messenger RNA levels in human skin fibroblast J Invest Dermatol 90 : 420 – 424 21 Phillips CL et al (1994) Effects of ascorbic acid on proliferation and collagen synthesis in relation to the donor age of human dermal fibroblasts J Invest Dermatol 103 : 22 8 23 2 22 Nusgens BV et al (20 01) Topically applied vitamin C enhances the mRNA level of collagens I and III, their processing... fibroblast cell cultures [ 72] The sequence LysThr-Thr-Lys-Ser (KTTKS) has a fatty acid moiety called palmitoyl added to it in order to enhance its penetration in to the skin Sederma (Le Perray en Yvelines, France), the company that holds the patents to pal-KTTKS (Matrixyl), sponsored a study that was presented as a poster at the 20 02 World Congress of Dermatology in Paris, France In this 4-month study, palKTTKS... products The potential uses of beta-glucans in dermatology are numerous In personal-care products for shaving, where nicks and cuts, razor burn, irritation and folliculitis are problematic, the protective, wound-healing, anti-irritating effects of beta-glucans can be quite helpful The photoprotective effects of beta-glucans as well as their ability to soothe, moisturize, and protect the skin from potential... polyphenolic antioxidants and skin photoprotection Int J Oncol 18 : 1307–13013 36 Katiyar SK (20 01) Green tea polyphenol (–)-epigallocatechin-3-gallatetreatment to mouse skin prevents UVB-induced infiltration of leukocytes, depletion of antigen-presenting cells, and oxidative stress J Leukoc Biol 69 : 719– 726 37 Bagchi D et al (20 00) Free radicals and grape seed proanthocyanidin extract: importance in human health . UVB-induced immunosuppression in mice by the green tea polyphenol (-) -epigallocatechin-3-gallate may be associated with alterations in IL-10 and IL- 12 production. Carcinogenesis 20 : 21 17 21 24 34 . 22 2. 6 B Vitamins . . . . . . . . . . . . . . . 23 2. 7 Alpha-Hydroxy Acids (AHAs) . . . . . 23 2. 8 Polyhydroxy Acids (PHAs) . . . . . . . 24 2. 9 Beta-Hydroxy Acids (BHAs) . . . . . . 24 2. 10. Met- ab 82 :22 15 22 21 28 . Bengtsson BA, Johannsson G, Shalet SM, Simpson H, Sonken PH (20 00) Treatment of growth hormone deficiency in adults. J Clin Endocrinol Metab 85: 933–9 42 29. Drake

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